This work shows that the Japan Gigabit Network (JGN) was initiated to create an environment enabling research and development of the infrastructure, middleware, and application technologies that would become necessary when a gigabit class network environment was introduced, and to accelerate this research and development. It shows that the JGN project has achieved many fruits, both domestic and international, academic and industrial. The source of these successes lies in the fact that the JGN provided an environment where the results of researchers' efforts are tested and evaluated in actual and practical use, and that the architecture and operation of this environment was in turn performed directly by the researchers themselves. Thus, the continuous operation of a new IT infrastructure on a trial basis has proved a valuable policy for the promotion of Japan's information and communication technology research.